LiqrSicc

I'm driving my Rx and all of a sudden the check engine light goes on. It didnt really bother be and the first thing that came to mind was the MAF sensor since I did put a K&N filter in a few months back. I stopped at AutoZone to see if they could check my codes and they told me they didnt do that. I always thought they did? They tried to say I can rent the scanner for about $140. I passed on it and decided to make my way down to the store about 10 miles down. About halfway there my subs just started to sound distorted and my amp then turned off as well as my deck. I pulled over to check it out and my subs were fine, I thought I had blown them. I go over to check my capacitor and the voltage readout says 12.5v. Normally it's in the high 14v for me, so I was wondering what was goin on. I popped the hood to check the battery and the alternator and everything seemed fine. By the time I looked again the voltage was down to 9.6v. I decided to start the car back up and all the lights on my dash were acting wierd, Looked back and the voltage was down to the 8s. I stepped on the gas and my car would not go more than 15mph. I thought it was over then out of nowhere my car comes back to life. I turn back and my voltage is back at 14. So the car drives fine, but levels off at 12v, which is normal right? I make it to the store to do my shopping and manage to leave the parking lot fine. I'm about 3 miles from home and I turn around and the voltage reading is back to 10v. My lights were so dim I barely made it back. It got all the way down to about 8v again and when I thought it was gonna die for good, BAM, back to 14.4v. I made it home, parked and my voltage read at 10v while idling. I turned off the engine and for some reason the voltage started climbing up. What is goin on? This is my only car, I cant afford for it to go out on me. Can anybody help me out here? I seriously dont know what it is.

Carver

How old is your battery?

LiqrSicc

Its an Optima Yellowtop bought less than a year ago. I'm not sure if its the battery considering the voltage still jumps up to the high 14s.

salimshah

loose wire/bad terminal or use comes to mind.

Next would be bad load [add on electronics or alarm].

Although unlikely but an overnight charge can help the yellow top.

Salim

Lil4X

Voltage should be 13.8 - 14.4 with the engine running. It shouldn't drop below 11.2 - 11.8 with the engine off. It sounds like you may have a bad alternator, and/or a dead short somewhere else in your system that is dragging the system down. Go to Auto Zone and have your battery tested under load (in the car with normal accessories and lights on.)

I think Salim's on the right track here, and certainly has a lot more experience than most of us. DC electrics can be extremely frustrating to troubleshoot, but as a guess, I'd start looking at your aftermarket add-ons, too. Try disconnecting the sound system, particularly the amps and capacitor - these can produce a pretty dramatic short without making smoke, thanks to the heavy-gauge wiring. Put a voltmeter across your battery terminals as you have someone switch loads on and off and watch what happens. Voltage falling into single digits is a sure sign of trouble. You seem to have an intermittent problem - and only a lot of creative switching, contact cleaning, and wire-wiggling is likely to find it.

LiqrSicc

I decided to take the chance and take my car to the mall since its been starting up fine and voltage staying at around 12. I got to the mall fine, but as soon as I left the voltage kept dropping and finally the car just died when it reached 8v. It would not start and 21st Century was giving me a hard time trying to get it towed. I had a friend who came by and it took about 5 minutes to charge up and jump start the car. After a few seconds the voltage just started dropping again so I pulled over. We jumped it again and I managed to find a safe spot to park overnight. I'm guessing its the battery, which really disappoints me since its less than a year old (still under warranty too). I'm hoping its not the alternator, which is a hi-output one that I ordered from Ace Alternators) and is only 3 months old. Well I'm gonna go and get a new yellowtop tomorrow. Hopefully that will fix the problem.

Lexmex

I can tell you this that when a dry cell battery goes, I had a friend with a Stinger have this problem and have read of a few cases involving Optimas, and they are virtually impossible to charge up again once they get into this funk where they lose power, unlike regular batteries where one may have chance. I would get an Optima with the most cranking amps you can get, whether that be a yellow or a red depending on your needs.

salimshah

Working with a well charged (new) battery seems like a good idea as it eliminates a major cause of problems.

my 2c on battery: I would reccomed red top over yellow. Yellow is a better alternative if you run accessories with the engine not running and that set up may require a deep overnight charge after extended battery use without engine running.

What you describe in your post falls under bizare/un-explainable. They fall genrally under the loose wire / intermittent short / intermittant load. The battery can have a open and cell shorts internally but usually with the engine running the alternator can overcome (within some limit) them.

After the battery replacement, use tactile (for spotting loose connection), visual ( to spot burnt wires) and smell (to detect smoke) to zero in. Carry a jumper cable and fire extinguisher till things become stable.

Salim

LiqrSicc

Thanks for the advice. I do run a heavy load on the battery. But even with a 1500watt amp using power, I still have a Stinger cell in my trunk and a 2 farad capacitor. Well basically my only problem right now is how I'm goin to get it back to my house without having to tow it. I might just get a battery charger and try to charge it to find out if it is the battery.

bob2200

This is specialized enough to custom/high-end audio that IMO you ought to have this thread transfered to the audio/electronics forum.

LiqrSicc

No need, solved the problem. Had nothin to do with my audio system. It was a bad alternator

salimshah

Please give details as we all learn from each other.

Normal alternator problems show up by "discharge lamp" lighting up and the battery is then not charged. This slowly drops voltage.

What you decribed was eratic voltage swings with no mention of discharge lamp. What brand of high amp alternator you have? Did you revert back to OEM alternator?

Salim

LiqrSicc

I had a hi-output 180amp alternator I bought on ebay from Ace Alternators. It was a remanufactured ND alternator that was made to fit the RX300. Looks exactly like the OEM but without the sticker. I made a post a few months back to get some feedback from everybody but didnt really get a helpful response so I just did my own research on Ace and seen they have been in the business for awhile, and they had 350+ 100% positive feedback on ebay. So I went along and bought it, had it installed , and was running like a champ until the other night.

What caused it to go out on me, I have no idea. I seriously did not see the discharge lamp go on. The CEL just came on one day and a little later after than the voltage drops. Now the voltage swing, I think I figured it out. The reason for the voltage dropping low, then suddenly picking back up was because I have a second battery in the trunk. I completely forgot about that dry cell. I had bought a battery charger and it confimed the battery was fine and the alternator was the problem. I finally found somebody to replace my alternator today with the stock one I had from before. What a savior, on Christmas eve. I feel kinda bad, he was getting shocked all over the place becasue I forgot to mention that I had a second battery.

Needless to say my car is running 100% again. No CEL and my capacitor is reading at 15v when the car is running. Thankfully I have a 1year warranty on the alternator and will be shipping back on tuesday.

BTW, this might be old news, who knows, but I learned a little trick from the mechanic. A quick way to see if your alternator is working is, with your engine running, take a screwdriver and carefully point it close to the alternator pulley. If alternator is working corrrectly, you'll feel the magnetic force pull the screwdriver. Pretty neat.

salimshah

Thanks for the info.

I hope you have in-line choke (inductance) to the 1 farad capacitors. [+12v->choke->cap+]. These large caps act as a short when they are discharged and really hammer the supply [battery or alternator]. The chokes prevent sudden current surge and help build up the voltage on the cap a bit gradually.

Enjoy the christmas.

Salim

DetMich1

Glad to hear your problem is solved.
Another way to demonstrate proper function of alternator is to disconnect the battery cable while engine is running. If alternator is producing current the engine will run even with no battery connected. If alternator fails while driving and discharge warning light comes on, you are running on current provided by battery. In this situation if you have to keep driving, you should turn off all unneccessary electrical accessories ie, stereo, heater fan, lights etc.